The invention relates to an elongate heater for heating an advancing synthetic filament yarn and which is particularly adapted for use in a yarn false twist crimping machine.
An elongate yarn heater of this type is known from EP 0 406 673 and corresponding U.S. Pat. No. 5,339,617. This known configuration of the elongate heater is based on the recognition that the transferable amount of heat is dependent on the radius of curvature of the heater. Logically, this improved transfer of heat is due to the fact that the decrease in the radius of curvature is accompanied by an increase in contact forces of the yarn on the elongate heater, and that therefore a more intimate contact exists between the yarn and the heater.
An increased curvature, however, results in the disadvantage of a greater looping friction. In the known elongate heater, this disadvantage is alleviated, at least in part, in that the heater is permitted to be shortened.
It is an object of the present invention to provide a yarn heater of the described type which eliminates as much as possible the disadvantage of the looping friction, which is associated with every curved, elongate heater, so that the looping friction is practically negligible.